This application relates to U.S. application Ser. No. 08/910,438, "High-Speed Decompressor" Attorney Docket No. D/95273QI (Common Assignee) Filed concurrently herewith., which is a continuation-in-part of U.S. patent application Ser. No. 08/502,841, filed Jul. 11, 1995, now abandoned.
This invention relates generally to retrieval of an electronically compressed document and more particularly concerns a decompressor in which a decompressor is used for decoding CCITT, IBMMR and TIFF codes and supplying generally at least four bits of decompressed data to a high speed printing engine at each clock cycle.
With a growing need for faster printing engines, the need for faster decompressors is also growing. A fast printing engine needs a decompressor to provide a flow of decompressed data with a speed which matches the consumption rate of decompressed data by the printing engine. If the decompressor is slower than the print engine, then a gap will be shown on the printed document.
Usually, the codes, which represent the frequent color changes on the document, slow down the decompressor. Among all the codes of CCITT two-dimensional compression algorithm, IBMMR and TIFF codes some codes can potentially generate only one bit data. A sequence of these codes will result in worst case performance, which is the most frequent change of color. This effect slows down the flow of data to the printing engine.
There are decompressors which can generate two bits of decompressed data every clock cycle. However, there is still a need to further increase the speed of the decompressors.
It is an object of this invention to increase the speed of decompressing the CCITT, IBMMR and TIFF codes by generally providing four bits of decompressed data at each clock cycle. Hereinafter, for the purpose of simplicity only the CCITT codes are discussed. However, it should be noted that the disclosed embodiment of this invention can be utilized to decompress CCITT codes as well as IBMMR and TIFF codes.